The anatomy of the interatrial septum: a transesophageal echocardiographic study

3D printing tissue-mimicking materials for realistic transseptal puncture models

Applications of additive manufacturing (commonly referred to as 3D printing) in direct fabrication of models for pre-surgical planning, functional testing, and medical training are on the rise. However, one current limitation to the accuracy of models for cardiovascular procedural training is a lack of printable materials that accurately mimic human tissue. Most of the available elastomeric materials lack mechanical properties representative of human tissues. To address the gap, the authors explore the multi-material capability of material jetting additive manufacturing to combine non-curing and photo-curing inks to achieve material properties that more closely replicate human tissues. The authors explore the impact of relative material concentration on tissue-relevant properties from puncture and tensile testing under submerged conditions. Further, the authors demonstrate the ability to mimic the mechanical properties of the fossa ovalis, which proves beneficial for accurately simulating transseptal punctures. A fossa ovalis mimic was printed and assembled within a full patient-specific heart model for validation, where it exhibited accuracy in both mechanical properties and geometry. The explored material combination provides the opportunity to fabricate future medical models that are more realistic and better suited for pre-surgical planning and medical student training. This will ultimately guide safer, more efficient practices.

Measurement of interatrial septal thickness by echocardiography in patients with moderate to severe rheumatic mitral stenosis undergoing percutaneous balloon mitral valvuloplasty

Background

Longstanding severe rheumatic mitral stenosis (MS) is associated with changes in the atrial chamber dimensions. It is not known whether there is an increased thickness of the inter-atrial septum (IAS) in patients with severe rheumatic mitral stenosis. The objective of this study was to evaluate pre-procedural IAS thickness by echocardiography in patients with moderate to severe rheumatic mitral stenosis undergoing percutaneous balloon mitral valvuloplasty (PBMV).

Methods

The thickness of the IAS was measured by transesophageal echocardiography (TEE) in 86 patients between 14 and 65 years of age. Patients with moderate to severe rheumatic mitral stenosis undergoing percutaneous mitral balloon valvuloplasty (PMBV) at the National Institute of Cardiovascular Diseases (NICVD), Karachi were recruited for this study. IAS thickness was measured by TEE using standard views and 3 different phases of cardiac cycles were evaluated.

Results

Out of 86 patients, almost three fourths (73.3%) were between 14 and 29 years of age and two thirds (62.8%) were females. Mean IAS thickness was 2.56 (SD 0.92) mm at anterior region (AR), 1.89 (SD 0.75) mm at fossa ovalis (FO), and 2.95 (SD 0.97) mm at posterior region (PR). None of the demographic and clinical groups showed any statistically significant difference in IAS thickness.

Conclusions

Inter-atrial septum (IAS) thickness measurement does not change in the presence of moderate to severe rheumatic mitral stenosis as compared to the reported normal values of IAS thickness in cadaveric hearts.

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Understanding of the anatomy of atrial septum is important for the interventionist for safe and effective performance of trans-septal puncture.

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Echocardiography is the preferred imaging modality for evaluating the IAS.

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IAS thickness measurement by echocardiography provides a reasonable roadmap to guide transseptal puncture.

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IAS thickness measurement does not change in the presence of moderate to severe rheumatic mitral stenosis.

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A pre-procedural TEE may be sufficient for assessment of IAS thickness and anatomy relevant to the performance of transseptal procedures.

Spectrum of morphological abnormalities and treatment outcomes in ostium secundum type of atrial septal defects: Single center experience in >500 cases

BACKGROUND

Transcatheter closure (TCC) has emerged as the first line treatment option for secundum type of atrial septal defects (ASD). Outcomes of TCC depend upon proper delineation of defect anatomy by transesophageal echocardiography (TEE). Stability and proper placement of the device mandates adequate rims and proper alignment to the septum. Failed or unfavorable morphology for TCC requires referral for surgical repair.

METHODS

We prospectively analyzed the ASD patients who were referred for treatment. The morphological features of the defect were evaluated and the outcomes of TCC studied. Patients who undergo TCC and surgical repair were followed for immediate and long-term outcome comparison.

RESULTS

Of the 512 patients who underwent treatment, TCC was attempted in 430/512 (83.2%) patients. It was successful in 393/430 (91.3%) patients. The remaining 119 patients underwent surgical patch closure. Twenty patients had failure of device alignment and device embolization occurred in 17 patients. Very large defect size ≥35 mm, absent or deficient posterior rim, absent/deficient inferior naval rim showed high chances for failure and formed major reasons for surgical referral. The surgical group had higher success (100%) across all anatomic variables. However, they had longer intensive care unit (ICU) and hospital stay (p < 0.001).

CONCLUSION

TCC offered a success rate of 91% in complex defects after TEE selection. Very large size and deficient inferior, posterior rims predicted failure of TCC. Surgery offered 100% success and it involved a longer hospital and ICU stay. The long-term clinical results were identical with both treatment modalities.

Impact of modified techniques of transcatheter closure in large atrial septal defects (⩾30 mm) with anatomic complexities

OBJECTIVE

The outcome of transcatheter closure in ostium secundum atrial septal defects is determined by the morphology of the defects. Modified techniques such as balloon assistance, pulmonary vein deployment, left atrial roof technique, and so on are used for circumventing the anatomic complexities and increasing the success rates.

METHODS

We planned a prospective study looking at the outcomes of transcatheter closure in secundum atrial septal defects with modified techniques in different anatomic complexities identified in transoesophageal echocardiography and their association with outcome of transcatheter closure.

RESULTS

Transcatheter closure was successful in 295 out of 346 (82%) patients with modified techniques. Balloon-assisted technique offered a success rate of 87%. The mean defect size was 34.7±2.78 mm (95% confidence interval (CI) 30.67-43.1 mm) with success and 40.16±4.5 mm (95% CI 32.16-44.7) with failure (p = 0.02). The mean total septal length was 38.11±0.63 (95% CI 35.21-40.56 mm) with success and 42.54±0.34 (95% CI 38.79-43.21 mm) with failure. The defect to septal ratios were 0.82 and 0.94 in success and failure groups, respectively (p=0.02). However, the absence of a retro-aortic margin, septal aneurysm, and multiple defects did not affect the success rate. Deficient inferior vena caval margin, deficient posterior margin, and size⩾40 mm had a high risk of failure with transcatheter closure. The odds ratio for procedural failure was 25.3 (4.3-143.8) in patients with malaligned septum, 8.3(1.4-48.5) with deficient inferior vena caval margin, and 4.1(2.5-19) for size⩾40 mm.

CONCLUSIONS

The modified techniques for device deployment offer substantial chances of success in transcatheter closure of secundum atrial septal defects with anatomical complexity (82%). Variants such as defect size of⩾40 mm and deficient inferior and posterior margins have high failure rates with a modified technique.

Recognizing and reacting to complications of trans-septal puncture

INTRODUCTION

The transseptal puncture (TSP) enables access to the left heart, through the fossa ovalis (FO), both in electrophysiology and in cardiac interventional procedures. TSP is usually safe in experienced hands. Sometimes TSP can be technically demanding and carries the risk of severe complications in approximately 1%. While performing a TSP, every effort should be taken in order to avoid complications. In the event of complications, prompt recognition and reaction are essential and a combined 'heart-team' management may be the most effective approach. Areas covered: Main TSP-related complications are cardiac tamponade, aortic root puncture, embolic stroke, transient ST elevation of inferior leads and iatrogenic atrial septal defect. A challenging TSP may be expected in presence of difficult IAS-FO anatomies, previous TSP, IAS occluder device and previous IAS surgical repair. Use of echo imaging and special needles (ie., radiofrequency needle and J-shaped guidewire) may avoid TSP-related complications in difficult settings. Expert commentary: Some tools are available to help minimize the risks of TSP. However, their availability might be limited. To increase safety of TSP, an adequate training of physicians, identification of patients in whom it might be difficult and a prompt recognition of complications seem to be the most important background.

Anatomy of the atria : A road map to the left atrial appendage

The left atrial appendage (LAA) has received increasing attention in recent years because of thrombi formation in patients with atrial fibrillation, which increases the risk of stroke. In patients who have contraindications for long-term oral anticoagulation therapy, percutaneous procedures are used to occlude the LAA and there are now several devices available for implantation, both endocardially and epicardially. Despite the high-resolution imaging techniques on hand today, limitations remain in providing information about wall thickness and neighboring structures; therefore, in-depth knowledge of the normal atrial anatomy is mandatory when considering such interventions. Here, the anatomy of the right and left atria is reviewed with relevance to interventional procedures required for LAA occlusion. The components of the atria, particularly the LAA as well as the atrial septum, are described with emphasis on their spatial relationships to neighboring cardiac and extracardiac structures. Sound knowledge of the atrial anatomy including endocardial and epicardial aspects is necessary. This will help interventionists take full advantage of imaging techniques when assessing the suitability of the LAA anatomy for closure, selecting the optimal device types and sizes, and guiding the LAA closure procedure, thereby reducing potential complications and increasing procedural success.

Transseptal puncture - Review of anatomy, techniques, complications and challenges

In recent years, the transseptal puncture approach has enabled passage of increasingly large and complex devices into the left atrium. Traditional tools remain effective in creating and dilating the initial puncture, with an acceptable safety profile. Even for skilled operators, the procedure is technically demanding and requires sound understanding of atrial anatomy. Intracardiac echocardiography is useful in cases of previous septal repair, poorly defined fossa ovalis anatomy or when considering patent foramen ovale portal crossing. Iatrogenic atrial septal defect (iASD) is the most commonly encountered long-term complication and there is increasing evidence that larger devices are leading to symptomatic defects. The size of the sheath crossing the septum is the strongest predictor of iASD formation but other factors such as longer procedure times, significant catheter manipulation and high pulmonary pressures also contribute. Transcatheter mitral valve repair involves the use of large 22 Fr catheters which carry alarmingly high rates of defect persistence with precipitation of symptoms and possible influence on mortality. Long-term follow up data, particularly beyond the 12-month period are lacking and resultantly, evidence to guide management is sparse. Refinements of conventional instruments, as well as innovations to puncture the septum without mechanical pressure, herald a progressively safer future for the transseptal technique.

Pathophysiology of paradoxical embolism: evaluation of the role of interatrial septum anatomy based on the intracardiac echocardiography assessment of patients with right-to-left shunting

BACKGROUND

Detailed anatomic variants of the interatrial septum in patients with right-to-left shunt and contribution of specific anatomies to the risk of ischaemic recurrences has not yet been comprehensively classified.

OBJECTIVE

To report a classification of the anatomic variants of the interatrial septum as observed by intracardiac echocardiography and its correlation with clinical and functional characteristics.

METHODS

We retrospectively reviewed the medical and instrumental data of 520 consecutive patients (mean age 44±15. 5 years, 355 women) who had over a 10-year period undergone intracardiac echocardiography and right-to-left shunt catheter-based closure. The four main features used to analyse were: (a) diameter of the oval fossa, (b) presence and length of the channel, (c) presence and degree of atrial septal aneurysm, and (d) rim thickness. The presence of Eustachian valve was also tabulated.

RESULTS

The combinations of interatrial septum anatomical features were classified into six main anatomical subgroups. Recurrent embolism, multiple ischaemic foci on brain magnetic resonance imaging, high grade shunt, and permanent shunt before transcatheter closure procedure were associated with type 2, type 4, and type 6. Type 4 anatomical subtype (OR 4.1, 1.5-8 [95% CI], p<0.001) and type 2+presence of Eustachian valve (OR 4.3, 1.6-9 [95% CI], p<0.001) were the strongest predictors of recurrent ischaemic events before transcatheter closure.

CONCLUSION

Our study showed that interatrial septum anatomy greatly differs among patients with right-to-left shunt, as well as the risk of ischaemic recurrences in different anatomies.

Usefulness of intracardiac echocardiography with a mechanical probe for catheter-based interventions: a 10-year prospective registry

BACKGROUND

The clinical outcome benefit of intracardiac echocardiography (ICE) with a mechanical probe during congenital heart disease interventions has not been fully investigated. We reported the long-term results of a prospective registry of interatrial shunt closure guided by mechanical ICE.

METHODS

We enrolled 537 patients (mean age 48 ± 19.0 years, 378 females) submitted to ICE-aided procedures in a prospective registry over a 10-year period (September 2003-September 2013). All patients underwent transesophageal echocardiography (TEE) before the planned procedure. We evaluated (1) structure identification capability, (2) fossa ovale and interatrial septum component measurement, (3) procedure monitoring capability, (4) procedural and fluoroscopy times, and radiograph dose, (5) probe-related complications.

RESULTS

ICE was successfully performed and was able to correctly identify the structures previously assessed by TEE in all patients. In 24 patients (4.5%), ICE allowed better anatomy definition than TEE. In 35 other patients (6.5%), ICE identified structures not observed by TEE, which led to change indications to interventions or the operative technique to be used. In 131 patients (24.4%), ICE evaluation led to change the planned device to be implanted. There was only one probe-related complication (0.2%).

CONCLUSIONS

Mechanical ICE may offer a valid alternative to conventional TEE in guiding congenital heart disease interventional procedures.

Left atrial anatomy relevant to catheter ablation

The rapid development of interventional procedures for the treatment of arrhythmias in humans, especially the use of catheter ablation techniques, has renewed interest in cardiac anatomy. Although the substrates of atrial fibrillation (AF), its initiation and maintenance, remain to be fully elucidated, catheter ablation in the left atrium (LA) has become a common therapeutic option for patients with this arrhythmia. Using ablation catheters, various isolation lines and focal targets are created, the majority of which are based on gross anatomical, electroanatomical, and myoarchitectual patterns of the left atrial wall. Our aim was therefore to review the gross morphological and architectural features of the LA and their relations to extracardiac structures. The latter have also become relevant because extracardiac complications of AF ablation can occur, due to injuries to the phrenic and vagal plexus nerves, adjacent coronary arteries, or the esophageal wall causing devastating consequences.

Utility of balloon assisted technique in trans catheter closure of very large (≥35 mm) atrial septal defects

BACKGROUND

Very few published data is available on the outcomes of balloon assisted techniques (BATs) for trans catheter closure (TCC) of very large (Defined as ≥35 mm size) ostium secundum atrial septal defect (ASD).

OBJECTIVE

To study the utility of BAT as against conventional techniques (CT) in TCC of very large ostium secundum ASD (≥35 mm) over the past 5-year period and to find out the association of different morphological features of the defects in relation to TCC outcomes.

STUDY DESIGN AND METHODS

Descriptive single center retrospective study of patients with very large ostium secundum ASD (≥35 mm size) who were subjected to TCC.

RESULTS

Thirty-three out of 36 patients with ≥35 mm ASD and complex morphological features underwent successful TCC. The study patients had high prevalence of absent aortic and posterior rims with posterior mal-alignment of the septum. BAT was successful in 28/31 (90.3%) patients while CT had a success rate of 16%. The mean trans-esophageal echocardiography (TEE) ASD size with BAT success 37 (SD 1.3) mm and CT failure 36.2 (SD 1.1) mm was not different (P=0.06). On univariate analysis of different morphological features, posterior mal alignment of the septum was associated failure of CT (P=0.01). There was no urgent referral for surgery and patients did well on follow up.

CONCLUSIONS

Balloon assisted device closure of (≥35 mm) ASD had 90% success rate. BAT helps in controlled delivery and device alignment in very large ASD with posterior malalignment of the septum and is often helpful when CT fails.

Techniques and outcomes of transcatheter closure of complex atrial septal defects - single center experience

OBJECTIVE

To prospectively study the techniques and outcomes of transcatheter closure of complex Atrial septal defects (ASD).

STUDY DESIGN AND SETTINGS

Prospective single center study with experience in catheter closure of ASD. All patients with complex ASD suitable for device closure.

OBJECTIVE

Analysis of outcomes of transcatheter closure of complex ASD in JIPMER Hospital over the past 5-year period.

METHODS

Complex ASD was predefined and patients satisfying inclusion and exclusion criteria are included. All the patients had meticulous Transesophageal echocardiography (TEE) imaging beforehand. Modifications of the conventional techniques were allowed on a case per case basis according to operator preference. Successfully intervened patients were followed up clinically.

RESULTS

Out of the 75 patients enrolled, 69 patients had successful device closure (success rate 92%) despite challenging anatomy. Fifty-six (74%) patients had ASD ≥ 25 mm. Fifteen patients (20%) had defect size ≥ 35 mm and 20 patients (26.6%) had devices implanted with ≥ 35 mm waist size. Fifty percent of patients had complete absence of aortic rim and 25% had deficient posterior rim. Twenty percent of patients had malaligned septum. Mean follow up period was 3.2 years.

CONCLUSIONS

Trans catheter closure is feasible in anatomically complex substrates of Secundum ASD. Careful case selection, scrupulous imaging protocol, and expertise in modified techniques are mandatory for successful outcomes.

Anatomy of the left atrium for interventional echocardiography

The anatomy of the left atrium is reviewed with relevance to various interventional transcatheter procedures requiring manoeuvres within or passage through the left atrium. The component parts of the atrium--the atrial body with a vestibule, appendage, venous component, and the atrial septum--are described with emphasis on their spatial relationships to neighbouring cardiac and extra-cardiac structures. Normal variations are discussed for a better understanding of the anatomy so as to reduce the risk of potential complications during procedures.

Three-dimensional imaging of the atrial septum and patent foramen ovale anatomy: defining the morphological phenotypes of patent foramen ovale

Patent foramen ovale (PFO) is known to occur with greater prevalence in those with cryptogenic stroke. These observations support the role of a PFO as a channel for paradoxical embolism and a mechanism for cerebral ischaemic events. Transcatheter closure of PFO may be indicated in this setting. A prerequisite of procedural success is achieving complete closure of the shunt. Studies have shown a varying degree of successful shunt closure. Residual shunts are usually the result of a mismatch between the device shape and PFO anatomy. In this article, we review the features of PFO and their surrounding structures as seen by three-dimensional transoesophageal echocardiography in patients undergoing transcatheter closure and relate these to the variations in morphology on anatomical specimens for a better appreciation of their suitability for closure devices. The salient features of the anatomical variations seen in adults undergoing transcatheter device closure have been summarized and used to produce a practical pre-procedural checklist.

Patent foramen ovale: a comprehensive review for pulmonologists

PURPOSE OF REVIEW

A comprehensive review of the main concepts about patent foramen ovale (PFO) management is offered.

RECENT FINDINGS

PFO is a common, usually benign, anatomical variant that in the presence of a discrete right-to-left shunt and other predisposing factors (Eustachian valve/Chiari network, atrial septal aneurysm, and coagulation cascade abnormalities) may play an important role in the patho-physiology of paradoxical embolism at different levels (cryptogenic stroke, peripheral embolism, coronary embolism, etc.). Therapy is a controversial issue, since data on these patients are variable and accepted guidelines are missing. Recurrent strokes are the most diffuse and accepted indication for transcatheter closure of PFO, but severe refractory migraine with aura, unexplained oxygen desaturation, orthodeoxia-platypnea, and other conditions have been suggested to benefit from PFO closure. Different devices and techniques have been proposed for this procedure, mainly depending on operator experience and preferences, which have contributed to this intervention becoming a well tolerated and effective procedure with very low morbidity and virtually absent mortality.

SUMMARY

PFO management is still a debated field: indications, pathophysiology and ideal closure techniques remain to be fully clarified and investigated before considering PFO closure a routine procedure.

Pre-procedural planning for percutaneous atrial septal defect closure: transesophageal echocardiography compared with cardiac computed tomographic angiography

BACKGROUND

The safety and efficacy of percutaneous closure of atrial septal defects (ASDs) is determined by several variables, including defect size, presence of adequate rim tissue, relationship to other cardiac structures, and associated congenital anomalies.

OBJECTIVE

We sought to determine the accuracy of computed tomographic angiography (CTA) in predicting a defect's size compared with pre-procedural transesophageal echocardiography (TEE) and to the current "gold standard" balloon sizing by intracardiac echocardiography (ICE).

METHODS

Thirty-five consecutive patients referred for possible percutaneous closure of suspected secundum ASD were evaluated with gated multislice CTA after initial TEE screening. Axial and sagittal image planes of the ASD from the CTA multiplanar reformation (MPR) images were used to measure the defect size and surface area.

RESULTS

Of the 35 patients with secundum-type ASDs, 5 subjects had disqualifying anatomy by CTA and 2 had an unsuccessful closure, resulting in a procedural success rate of 93%. Measurement of defect area by gated MPR images provided the strongest correlate to ICE balloon size. In large ASDs, TEE was less well correlated to the maximum defect size and identification of the inferior/inferoposterior rims than CTA.

CONCLUSIONS

Cardiac CTA is an accurate and useful technique for pre-procedural assessment of ASDs and may be superior to conventional TEE in large defects that have deficient inferior rims.

Transcatheter patent foramen ovale closure in spite of interatrial septum hypertrophy or lipomatosis: a case series

OBJECTIVE

Hypertrophy and lipomatosis of the interatrial septum have been thought to be contraindications for transcatheter patent foramen ovale (PFO) and atrial septal defect closure because of the limits of current devices and the risk of suboptimal results. No reports have been produced yet about PFO closure in patients with such conditions. We retrospectively assessed the safety and effectiveness of PFO closure in patients with hypertrophy or lipomatosis of fossa ovalis rims.

METHODS

We searched our database of 140 consecutive patients (mean age 43 +/- 15. 5 years, 98 female patients) who underwent transcatheter PFO closure for cases of hypertrophy or lipomatosis of the interatrial septum. All patients were screened with transesophageal echocardiography before the operation. All patients underwent intracardiac echocardiography study and attempted closure.

RESULTS

Ten patients (7.1%) underwent an attempt at transcatheter closure in the presence of hypertrophy of the rims (eight patients) or lipomatosis (two patients). All patients were aged more than 50 years and has multiple recurrent stroke events (nine patients) or need for a posterior cerebral surgical procedure (one patient) making closure mandatory. After intracardiac echocardiography study and measurements, two 25 mm Amplatzer and eight 25 mm Premere Occlusion System devices have been implanted successfully. On mean follow-up of 36.6 +/- 14.8 months, two patients had a small residual shunt: no recurrence of stroke or aortic erosion or device thrombosis was observed during this period.

CONCLUSION

Transcatheter PFO closure in the presence of hypertrophy or lipomatosis of fossa ovalis rims is not contraindicated per se: careful evaluation of rim thickness with intracardiac echocardiography and selection of soft and asymmetrically opening devices may allow for a safe and effective PFO closure, at least in patients with no severe atrial septal aneurysm.

The importance of atrial structure and fibers

Atrial structures are important in the current era of cardiac interventions using percutaneous transcatheter procedures. Understanding their locations and component parts helps to reduce risks of procedural-related damage. The general arrangement of the myofibers that make up the atrial walls is reviewed to provide a morphologic basis for atrial conduction and potential substrates of arrhythmias. The right atrium, dominated by its appendage, is characterized by having an extensive array of pectinate muscles. These extend almost perpendicularly from the terminal crest. The left atrium has relatively smooth walls and a small tubular-shaped appendage. The myofibers show changes in orientations when traced through the thickness of the walls. Extensions of atrial myocardium onto the pulmonary veins and the superior caval vein are common. Apart from Bachmann's bundle, there are other muscular bridges of variable numbers and sizes that provide interatrial connections, connections between the left atrium and the coronary sinus, and connections between the muscular sleeves of the right pulmonary veins and the right atrium. The purpose of this review is to summarize the three-dimensional arrangement of gross atrial structures, the myoarchitecture and variations in muscular interatrial connections. These are important features in intra- and interatrial conduction.

Clinical, laboratory, and transesophageal echocardiographic correlates of interatrial septal thickness: a population-based transesophageal echocardiographic study

BACKGROUND

The determinants of interatrial septal (IAS) thickening ("lipomatous hypertrophy"), a common echocardiographic finding in the elderly, are poorly defined. The objective of this study was to determine the clinical, laboratory, and transesophageal echocardiographic correlates of IAS thickening in the general population.

METHODS

The thickness of the IAS was measured by transesophageal echocardiography in 384 patients (median age: 66 years; range: 51-101 years; 53% men) participating in a population-based study (Stroke Prevention: Assessment of Risk in a Community). The associations between atherosclerosis risk factors, clinical cardiovascular disease, aortic atherosclerotic plaques, and IAS thickness were examined.

RESULTS

Age and body surface area (BSA) were significantly associated with IAS thickness (median: 6 mm; range: 2-17 mm). IAS thickness increased by 12.6% per 10 years of age (95% confidence interval: 9.0-16.4%) adjusting for sex and BSA, and increased by 7.0% per 0.1 m 2 BSA (confidence interval: 5.0-9.2%) adjusting for age and sex. Overall, age, sex, and BSA accounted for 22.5% of the variability in IAS thickness. Current smoking (20.4% increase in IAS thickness in current smokers) and hypertension treatment (8.5% increase in treated patients) were associated with increased IAS thickness, adjusting for age, sex, and BSA ( P < .05), but these two risk factor variables jointly explained only an additional 2.3% of the variability in IAS thickness beyond the variability explained by age, sex, and BSA. Clinical coronary artery and cerebrovascular disease, atrial arrhythmias, and aortic atherosclerotic plaques were not associated with IAS thickness, adjusting for age, sex, and BSA ( P > .3).

CONCLUSIONS

IAS thickening is an age-associated process. Atherosclerosis risk factors are weakly associated with IAS thickening, whereas atherosclerotic vascular disease is not.

The Importance of Increased Interatrial Septal Thickness in Patients with Atrial Fibrillation: A Transesophageal Echocardiographic Study

BACKGROUND

Histological studies in animal models have showed that extensive atrial fibrosis or fatty deposition as a result of loss of atrial cardiomyocytes increases the propensity to develop atrial fibrillation (AF). Although several reports have suggested that AF in humans may be a consequence of these mechanisms, no study has correlated the presence of AF with interatrial septal thickness (IAST).

METHODS

Accordingly, we conducted a prospective analysis in 150 consecutive patients referred for transesophageal echocardiography (TEE) for numerous medical reasons. A total of 105 patients (mean age 62 +/- 14 years) who met inclusion and exclusion criteria were included for analysis. Pertinent demographics, echocardiographic chamber dimensions, left ventricular ejection fraction (LVEF), color flow, and spectral Doppler analysis, as well as IAST measured in both systole (S) and diastole (D) were obtained.

RESULTS

When patients with a documented history of AF were compared to patients without documented AF, no statistical difference was noted in terms of patients' height, weight, IVS thickness, or LVEF. Patients with AF had a significantly larger left and right atrial dimensions (P < 0.001), lower left atrial appendage emptying velocities (P < 0.002), and pulmonary vein systolic Doppler signal (P < 0.01). The IAST in systole in patients with AF was 0.75 +/- 0.27 cm versus 0.60 +/- 0.16 cm in patients without AF (P < 0.006) while the IAST in diastole was 0.61 +/- 0.22 cm versus 0.49 +/- 0.12 cm, respectively (P < 0.009). However, no statistical difference was noted between IAST in either systole (P < 0.8) or diastole (P < 0.8) among patients with AF based on the duration of this arrhythmia.

CONCLUSIONS

The results of this prospective TEE study show a statistically significant increase in IAST with the presence of AF independent of patient's age, height, weight, and the degree of IVS thickness. In addition, since no significant valvular abnormalities or compromise in left ventricular systolic function were present, the increase in IAST in patients with AF then suggest possible changes in the material properties of the atrial wall, easily identified by TEE on the interatrial septum, either as a cause or as a result of AF. Since no correlation was found between the degree of IAST and the duration of AF, the presence of IAST not only might identify patients with a higher propensity to have or develop this atrial arrhythmia; but also be a surrogate marker of changes within the components of the atrial wall in AF.

Human Study of Biatrial Electrical Coupling

Background— The relative contribution of the atrial septum and interatrial connections to biatrial activation is a fundamental concept of human cardiac electrophysiology that has yet to be fully characterized. The purpose of the present study was to determine how both atria are coupled electrically.

Methods and Results— Twenty patients (16 men; mean age 54±11years) with a history of symptomatic atrial fibrillation (AF) underwent simultaneous biatrial noncontact mapping before catheter ablation of AF. The multiple electrode array catheters were positioned, respectively, in the left atrium (LA; transseptally) and the right atrium (RA). In all but 2 patients, isopotential maps revealed that endocardial septal activations of the RA and LA were separate, independent, and asynchronous of each other. Interatrial conduction was related to the site of initial atrial depolarization, revealing conduction over Bachmann’s bundle in all patients during sinus rhythm, high RA pacing, and pacing from the LA appendage. Pacing from the coronary sinus was associated with conduction over the interatrial connection at the level of the coronary sinus in all patients, and conduction over Bachmann’s bundle also occurred in 5 (26%) of 19 patients. Interatrial conduction over the fossa ovalis occurred in only 2 (2%) of the 116 segments analyzed.

Conclusions— Electrical coupling of the RA and LA in humans is predominantly provided by muscular connections at the level of Bachmann’s bundle and the coronary sinus. The true septum (the fossa ovalis and its limbus) of the RA and LA is asynchronous and discordant, usually without contralateral conduction during sinus rhythm or atrial pacing.

The role of echocardiography in transcatheter closure of atrial septal defects

Closure of so-called "secundum" atrial septal defects with a device inserted on a catheter necessitates precise delineation of their morphology. Echocardiography is the diagnostic method of choice to demonstrate this morphology, and to differentiate such defects located within the oval fossa from the other variants producing an interatrial communication. Precordial echocardiography usually allows selection of cases likely to be suitable for closure in this fashion. This selection is based on the localisation and the size of the deficiency in the oval fossa, the length of the interatrial septum, and the adequacy of the infolded rims surrounding the defect. Suitability for closure is reevaluated by transesophageal echocardiography, either as a separate investigation or at the start of the interventional catheterisation. This investigation requires a multiplane transesophageal echocardiographic probe, since only oblique planes will demonstrate the entrance of the systemic and pulmonary veins and their relationship to the defect. Transesophageal echocardiography serves as an important monitoring tool during the interventional procedure. As such, it is a necessary adjunct to fluoroscopy. The stretched diameter of the defect measured with a balloon is the main determinant of the choice of the type and size of the device. This diameter can be measured fluoroscopically, as well as on echo. Colorflow mapping serves to rule out residual shunting during the occlusion of the defect with the balloon. During deployment of the device, constant echocardiographic visualisation of the device and its position relative to the atrial septum facilitates proper placement. Such constant visualisation can only be provided by repeated quick acquisitions of multiple planes. Once the device is released, the investigator should continue to record the position of the device, and assess the potential for residual shunting. Most of the devices show some subtle change in position during the first 20 minutes after implantation.

Surgical validation and implications for transcatheter closure of quantitative echocardiographic evaluation of atrial septal defect

Accurate evaluation of secundum atrial septal defect (ASD) is important for the success of transcatheter closure. The purpose of this study was (1) to describe a quantitative evaluation by transthoracic (TTE) and transesophageal (TEE) echocardiography of the various morphologic features of ASD that might be important for patient selection for transcatheter closure, and (2) to assess the reliability of these 2 methods by surgical findings. Preoperative TTE and TEE were used to evaluate the ASD of 27 children undergoing surgical closure. Measurements included the diameters of ASD and the atrial septal lengths in the transverse and longitudinal axis, and the width of the superior, inferior, anteroinferior, and posterior septal margins. The shape and location of the ASD and the adequacy of the septal margins for anchoring occluding devices were determined. Echocardiographic data were compared with corresponding surgical measurements. No significant difference occurred in the means of all the parameters measured with the 3 methods, except for the transverse ASD diameter (p <0.05). Good agreement occurred between TTE and TEE and surgical data, except for the transverse ASD diameter, transverse atrial septal length, and the posterior septal margin on TTE. Intraclass correlations between TTE and TEE and surgical measurements of all parameters were good, except for the transverse ASD diameter. The accuracy in determining shape and location of the ASD by TTE and TEE were 100%, whereas that for determining the adequacy of septal margins was 98% and 97%, respectively. In conclusion, TTE and TEE are reliable methods for quantitative evaluation of ASD.

Intracardiac shunts

Unsuspected intracardiac shunts can be a cause of acute deterioration in critically ill patients. Shunts can be acquired or congenital conditions that become symptomatic only with changed physiologic conditions. Transesophageal echocardiography is an excellent tool for the diagnosis of intracardiac shunts.

Morpho-functional assessment of interatrial septum: a transesophageal echocardiographic study

BACKGROUND

Despite the increasing number of reports on lipomatous hypertrophy of interatrial septum, a standardization of measurement of the dimensions of the interatrial septum (IAS) in the different phases of cardiac cycle has not been reported. Moreover, no data on modification of thickness with age and in specific cardiac diseases are available.

OBJECTIVE

Our purpose was to study whether the changes of thickness and thinning of IAS may be related to age, left atrial dimension, cardiac cycle and different cardiac diseases.

METHODS

248 patients (mean age 52.7 +/- 19.9 years) underwent transthoracic (TTE) and transesophageal (TEE) echocardiography. IAS was measured at the constant regions anterior and posterior to the fossa ovalis. IAS thickness (tk), thinning (th) and % thinning (% th) were measured.

RESULTS

IAS thickness ranged from 4 to 13 mm at the time of ventricular end-systolic phase (mean 6.7 +/- 1.9 mm) and from 6 to 16 mm at the time of atrial systole (mean 9.9 +/- 1.8 mm); significant statistical difference between these values was found (P < 0.01). IAS thinning ranged from 1 to 7 mm (mean 3.42 +/- 1.8) while % IAS thinning from 18 to 76% (mean 36.53 +/- 16.36%). Statistical analysis showed a significant positive correlation between age and ventricular end-systolic thickness and atrial systolic thickness and thinning. An insignificant correlation was found between age and % IAS thinning and between left atrial dimension and IAS tk and th.

CONCLUSIONS

Our results demonstrate that IAS thickness increases by age; no correlation exists between IAS thinning and age. There is no difference between IAS thickness and thinning in patients with or without cardiac disease. We believe that the thickness of IAS can be considered hypertrophic only if it exceeds the value of 15 mm during both ventricular end-systolic and atrial systolic phases of the cardiac cycle. IAS thickness and thinning might be an additional parameter to evaluate systolic atrial function particularly with regard to maintenance of synus rhythm after conversion from atrial fibrillation as well as to better understand its role in determining the filling of ventricles in different clinical conditions.

Detection of left-to-right shunt in atrial septal defect by negative contrast echocardiography: a comparison of transthoracic and transesophageal approach

The occurrence of a right atrial negative contrast effect as an indicator of left-to-right shunt was studied in 101 patients with atrial septal defect by peripheral venous contrast injection during transthoracic and transesophageal echocardiography. Confirmation of the diagnosis was provided by cardiac catheterization or by autopsy in 72 (72%) patients. The defect could be visualized directly in 57 (57%) patients during the transthoracic and in 93 (93%) during the transesophageal examination (p < 0.001). A negative right atrial echo contrast effect was observed in 53 of 92 (58%) patients from the transthoracic and in 86 of 92 (93%) patients from the transesophageal approach (p < 0.001). Among these were seven (7%) patients with an aneurysmal interatrial septum but no directly visible defect during conventional transesophageal imaging. Appearance of contrast in the left atrium indicating right-to-left shunting was seen in 70 of 92 (76%) patients from the transthoracic and in 91 of 92 (99%) patients from the transesophageal approach (p < 0.001). Contrast injection during transesophageal imaging also helped identify additional malformations in 12 (12%) patients. Thus transesophageal echocardiography with echo contrast injection is a very reliable diagnostic method in patients with suspected atrial septal defect.

Echocardiographic follow-up of atrial septal defect after catheter closure by double-umbrella device

BACKGROUND

Transcatheter device occlusion of atrial septal defects is an attractive approach, but its efficacy and place in patient management remain to be determined.

METHODS AND RESULTS

To evaluate the medium-term results of atrial septal defect device occlusion and factors influencing residual shunting, transesophageal and transthoracic echocardiograms of 49 patients were reviewed. Transesophageal echocardiograms on 48 patients immediately following surgical closure revealed residual shunting in 2% compared with 91% after device occlusion; this proportion decreased to 53% after a mean follow-up of 10 months. The actuarial analysis suggests a progressive resolution of shunting with time. One patient had residual shunting by transesophageal echocardiography immediately after surgical closure compared with 29 after a mean follow-up of 10 months after device occlusion. Residual shunting was not influenced by (1) dimension, location, or position with relation to the device as assessed by transesophageal echocardiography; (2) location of the defect; or (3) device size relative to the stretched dimension of the defect. In 15 patients, a poor correlation existed between transesophageal and transthoracic echocardiographic findings. Variability in serial transthoracic echocardiographic findings was observed in 14. Right ventricular dimension, heart size, and presence of a murmur at follow-up did not correlate with the presence or size of residual shunting after device occlusion.

CONCLUSIONS

These results suggest that ongoing spontaneous resolution of residual shunting occurs after device insertion. Factors related to the defect or device could not predict eventual resolution of residual shunting. Transthoracic echocardiography in the follow-up of these patients may not be reliable in determining presence of residual shunting.

Transesophageal echocardiography as a tool in the evaluation of patients with embolic disorders

TEE has become one of the most powerful tools for evaluating patients with unexplained stroke, TIA, and peripheral and pulmonary embolization. This is especially encouraging in view of the previously disappointing results of TTE in these patients. In addition to the dramatic results in terms of clot visualization and the other intracardiac sources of embolization described previously, a new extracardiac source has been identified, namely protruding atheromas in the thoracic aorta. These atheromas have been seen for the first time because of the new diagnostic window that has been opened by the development of TEE. Their recognition and follow-up may lead to information that will change the approach to a significant number of patients with embolic ischemic episodes.

Echocardiographic Assessment of the Donor Interatrial Septumn in Heart Transplant Recipients

The donor interatrial septa of 46 heart transplant recipients were measured from 4 serial echocardiograms. The purpose of the study was to determine the thickness of the donor interatrial septum and to assess whether changes in the septal thickness occur over time, either with ischemic duration at the time of surgery or with the number of treated rejection episodes during the first year after transplant. This study showed that the donor interatrial septum has increased thickness after heart transplantation but returns to normal by the 12 months after transplant. However, there was no correlation with the number of treated rejection episodes or ischemic time.

Biplane transesophageal echo-Doppler studies of atrial septal defects: quantitative evaluation and monitoring for transcatheter closure

Forty-four patients with atrial septal defects, aged 7 months to 18 years (median 8.9), underwent biplane transesophageal (TEE) and transthoracic (TTE) echocardiography. The size of the defect and the shunt flow volume were measured by TEE and compared with the actual size at surgery (N = 14) or the shunt volume measured by the Fick method (N = 34), respectively. In all cases the location and morphology of the defect were clearly demonstrated by TEE; on the other hand, two patients with sinus venosus-type and multiple-type defects, respectively, and one with a small ostium primum defect did not have a complete diagnosis by TTE. The defect size determined by TEE correlated well with the surgical measurement. Similarly a significant correlation was demonstrated between the shunt volume measured by TEE and that obtained by the Fick method. In three patients transcatheter closure of the atrial septal defect by means of a clamshell device was accomplished successfully with TEE monitoring. We conclude that biplane TEE provides a better appreciation of cardiac anatomy and hemodynamic evaluation than TTE in this setting, and TEE is essential for monitoring during transcatheter closure.

Atrial septal defect after balloon mitral valvuloplasty: a transesophageal echocardiographic study

Fifty patients with rheumatic mitral stenosis aged twelve to thirty-six (twenty +/- six) years were studied by two-dimensional, pulsed and color Doppler echocardiography during, seventy-two hours after, and biweekly for three months after balloon mitral valvuloplasty (BMV). Transesophageal echocardiography (TEE) done immediately after BMV (in the catheterization laboratory) detected a new atrial septal defect (ASD) in 46 (92%) patients. These measured 1 to 2 (mean 1.2 +/- 0.3) mm in diameter. Doppler color flow mapping guided the location of the ASD in most of the cases. A narrow jet of left-to-right shunt could be evaluated by pulsed Doppler studies. Velocity time integral (VTI) of the jet across one cardiac cycle and the diameter of the ASD were used to calculate the left-to-right shunt (shunt = VTI x pi (D/2)2 x heart rate). The estimated shunt was 0.04-0.39 (mean 0.20 +/- 0.10) L/minute. A repeat study at seventy-two hours revealed the defect in 40 (80%) patients. At three months, the defect persisted in only 5 (10%) cases. The mean interval of closure of ASD was 4.6 +/- 2.2 weeks. The authors conclude: (1) ASD occurs commonly after BMV, (2) the septal defect and the resultant left-to-right shunt are insignificant, and (3) ASD disappears in the majority of cases by three months after BMV.

Response of the interatrial septum to transatrial pressure gradients and its potential for predicting pulmonary capillary wedge pressure: an intraoperative study using transesophageal echocardiography in patients during mechanical ventilation

OBJECTIVES

We hypothesized that the directional movement of the interatrial septum and its curvature may reflect the pressure relations between the left and right atria.

BACKGROUND

Interventricular septal shape is primarily dependent on the pressure gradient between the left and the right ventricle. No analogous study has carefully evaluated the determinants of interatrial septum shape and motion.

METHODS

Patients (n = 52) undergoing cardiac or vascular surgery were studied intraoperatively at multiple intervals with transesophageal echocardiography and simultaneous measurement of central venous pressure, pulmonary capillary wedge pressure and airway pressure.

RESULTS

Overall interatrial septum shape, which usually curved toward the right atrium, changed concordantly with the interatrial pressure gradient (pulmonary capillary wedge pressure-central venous pressure difference). The degree of interatrial septum curvature was also primarily dependent on the interatrial pressure gradient and, to a lesser extent, was affected by changes in left atrial size (F = 130.4 vs. F = 14.1). During passive mechanical expiration, the interatrial pressure gradient, usually positive, often reverses transiently and the interatrial septum momentarily bows toward the left atrium. Midsystolic reversal was seen in 64 of 72 episodes when the pulmonary capillary wedge pressure was < or = 15 mm Hg but in only 2 of 40 episodes when it was > 15 mm Hg (sensitivity = 0.89, specificity = 0.95, positive predictive value = 0.97).

CONCLUSIONS

These findings suggest that overall interatrial septum shape depends on the pressure gradient between the left and right atria. Midsystolic reversal of the interatrial septum, which probably reflects the increased venous return in the right relative to the left atrium during mechanical expiration, may be a useful indicator of the pulmonary capillary wedge pressure.

Biplane transesophageal echocardiography: an anatomic-ultrasonic-clinical correlative study

In 427 subjects TEE was performed with either a uniplane or biplane transducer; in seven cadavers the cardiac anatomic segments were observed in several levels and directions. Nine transverse and six longitudinal views were compared with the corresponding cardiac anatomic segments. Based on this correlative study, the levels of segments, insertion depth, anatomic structure identification, image characteristics, clinical applications, and the advantages as well as the limitations of biplane TEE are discussed.

Biplane transesophageal echocardiography: imaging sections and anatomic segments

In order to recognize correctly the images of transesophageal echocardiography (TEE), in 410 subjects TEE was performed with uniplane or biplane transducer, and in 7 corpses the cardiac anatomic segments were observed, at various levels and in different directions, 9 transverse and 6 longitudinal views were compared with the corresponding cardiac anatomic segments. Based on this study, the authors reported the levels of segments, insertion depth, anatomic structure identification, image characteristics and clinical application of TEE, and the advantages of biplane TEE are discussed.

Transesophageal echocardiography is superior to transthoracic echocardiography in the diagnosis of sinus venosus atrial septal defect

The purpose of this study was to compare transthoracic and transesophageal echocardiography in the diagnosis of various types of atrial septal defects. Forty-one adult patients with the clinical diagnosis of atrial septal defect were studied by transthoracic and transesophageal echocardiography (30 women, 11 men; 18 to 81 years of age). Transthoracic echocardiography demonstrated the atrial septal defect in 33 patients (secundum type in 28, primum type in 3 and sinus venosus type in 2). Transesophageal echocardiography demonstrated the defect in all 41 patients. Thus, in 8 (20%) of 41 patients the atrial septal defect was demonstrated by transesophageal and not by transthoracic echocardiography. Six of the eight had a sinus venosus type atrial septal defect; the other two patients had a secundum atrial septal defect (one of these two had a technically poor transthoracic echocardiogram and the other had a small atrial septal defect). Transthoracic echocardiography, therefore, failed to demonstrate the sinus venosus defect in six (75%) of eight patients. An anomalous venous connection associated with the sinus venosus defect was visualized by transesophageal echocardiography in seven of the eight patients but was not seen on transthoracic echocardiography in any patient. Sinus venosus type atrial septal defects are frequently not visualized in adults by conventional transthoracic echocardiography. Transesophageal echocardiography is recommended when an atrial septal defect is clinically suspected but cannot be visualized by transthoracic echocardiography.

Double-umbrella device for transvenous closure of patent ductus arteriosus and atrial septal defect: first experience

A new device for transcatheter closure of heart defects was constructed and used to close a patent ductus arteriosus (PDA) in seven adult patients and an atrial septal defect (ASD) in six adult patients. The device consisted of two self-opening umbrellas and a piece of Ivalon. A Dacron patch was sewn on the "male" umbrella for the ASD closure. The device required a 9 Fr introducing venous sheath for PDA and a 14 Fr sheath for the ASD. The venoarterial (right femoral vein-PDA or ASD-left femoral artery) long wire track was arranged. The "male" umbrella and the Ivalon were inserted transvenously one after another, advanced over the long wire across the PDA or ASD and extruded into the aorta or left atrium, respectively. The "female" umbrella was advanced transvenously over the long wire into the pulmonary artery (for PDA) or into the right atrium (for ASD). The metal conus on the long wire was used to pull the "male" umbrella while a special stiff pusher was used to bring the "female" umbrella to the "male" umbrella along the long wire. By these means the umbrellas interlocked at the defect level and closed it. The long wire was then removed through the left femoral artery. Protrusion of the interlocked device through the PDA occurred in one patient and through the ASD in two patients. In all three patients the device was kept on the wire until surgery and an early postrelease device embolization was avoided. In all other patients the defects were successfully closed. The follow-up of 3-27 months was uneventful in all patients. These results indicate that the described procedure is effective and safe, and warrants further clinical trial.